There has been proposed a conventional robot system that stops a behavior of a robot to ensure security around the robot when an external device such as an emergency stop switch is handled and a signal is input from the external device. This robot system has been known as disclosed in, for example, Japanese Patent No. 4196757.
The above robot system is configured to duplex signal lines for connecting external devices to a robot control unit that controls a behavior of a robot so as to surely input the signal from the external device into the robot control unit even if one of the signal lines has a trouble such as breaking of wire. As the signal line, there is widely known a so-called hard-wired signal line that transmits one signal by using one dedicated signal line.
In recent years, the type of external devices or the number of signals from the external devices tend to increase. Therefore, when two routes are configured in a hard-wired manner in the above duplex signal lines, the number of signal lines increases by two if the number of signals from the external devices increments by one, for example. It is concerned that connectors and a terminal part that bundle signal lines become larger and thus a space required for wiring increases, and this leads to totally grow the robot system in size, as the number of signal lines increases more as described above.